Variable imprinting of the MEST gene in human preimplantation embryos

Abstract

There is evidence that expression and methylation of the imprinted paternally expressed gene 1/mesoderm-specific transcript homologue (PEG1/MEST) gene may be affected by assisted reproductive technologies (ARTs) and infertility. In this study, we sought to assess the imprinting status of the MEST gene in a large cohort of in vitro-derived human preimplantation embryos, in order to characterise potentially adverse effects of ART and infertility on this locus in early human development. Embryonic genomic DNA from morula or blastocyst stage embryos was screened for a transcribed AflIII polymorphism in MEST and imprinting analysis was then performed in cDNA libraries derived from these embryos. In 10 heterozygous embryos, MEST expression was monoallelic in seven embryos, predominantly monoallelic in two embryos, and biallelic in one embryo. Screening of cDNA derived from 61 additional human preimplantation embryos, for which DNA for genotyping was unavailable, identified eight embryos with expression originating from both alleles (biallelic or predominantly monoallelic). In some embryos, therefore, the onset of imprinted MEST expression occurs during late preimplantation development. Variability in MEST imprinting was observed in both in vitro fertilization and intracytoplasmic sperm injection-derived embryos. Biallelic or predominantly monoallelic MEST expression was not associated with any one cause of infertility. Characterisation of the main MEST isoforms revealed that isoform 2 was detected in early development and was itself variably imprinted between embryos. To our knowledge, this report constitutes the largest expression study to date of genomic imprinting in human preimplantation embryos and reveals that for some imprinted genes, contrasting imprinting states exist between embryos.

Isoform-specific imprinting of the MEST gene in porcine parthenogenetic fetuses

“…For the amplification of the MEST-1C sequences, the PCR conditions and primer sequences are listed in Table S1. The PCR products were purified and subjected to BSP (10 positive clones) and Combined Bisulfite Restriction Analysis (COBRA) (Huntriss et al, 2013;Watanabe et al, 2010).…”

“…Multiple transcript isoforms of MEST have been identified as being imprinted in a tissue-and isoform-specific manner in humans and mice (Kosaki et al, 2000;Huntriss et al, 2013;Kamei et al, 2007), while there are no reports that MEST is isoform-specific imprinted in pigs. With this background, we are interested in identifying the imprinting status of porcine MEST isoforms by quantitative real-time PCR (qRT-PCR) and bisulfite sequencing PCR analysis (BSP) using parthenogenetic fetuses as a model.…”

Imprinted gene expression in hybrids: perturbed mechanisms and evolutionary implications

“…Lack of expression of this long non-coding RNA correlates with biallelic expression ('loss of imprinting') of IGF2R and of close-by placenta-specific genes (Monk et al, 2006). The growth-related PEG1/MEST gene on human chromosome 7q32 is polymorphically imprinted (Huntriss et al, 2013); its isoform-2 in placenta and early embryos is highly variable between conceptuses and this correlates with differential DNA methylation levels at an exonic differentially methylated region (McMinn et al, 2006).…”

H19 and MEST gene expression and histone modification in blastocysts cultured from vitrified and fresh two-cell mouse embryos

“…Mesoderm-specific transcript (MEST) is expressed in the paternal allele and encodes a alpha/beta hydrolase fold family enzyme with unknown function, which is located on proximal chromosome 6 in mice and chromosome 7q32 in humans (Huntriss et al, 2013). This gene is highly expressed in the early stage embryo, specifically in the mesodermal tissue (Kobayashi et al, 1997).…”

“…Some studies have shown that assisted reproductive technology influences DNA methylation and expression of MEST in humans and mice. It has been reported that hyper methylation of the MEST gene in differentially methylated region leads to Silver-Russel syndrome, which is thought to be caused by IVF (Huntriss et al, 2013;Imamura et al, 2005).…”